Brake and steering lock for castor

ABSTRACT

A castor ( 1 ) has a securing device (V) for blocking running action and/or steering action of a wheel ( 2 ) mounted in a fork ( 3 ). A mounting of the fork ( 3 ) permits pivoting about a vertical axis (y—y). A push rod ( 11 ) operates an integrally formed combination part (K) located at the fork for providing functions of braking-blocking and/or steering blocking formation. The push rod ( 11 ) carries a plate ( 23 ) configured for interacting with fork-mounted steering-blocking and braking-blocking parts of the combination part (K), which has steering-blocking mating protrusions ( 25 ) and braking-blocking means ( 26 ), these being located in spaced-apart planes (E′—E′, E″—E″).

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a castor having a securing device for blockingthe running and/or steering action of the running wheel mounted in afork, which fork itself is mounted such that it can be pivoted about avertical axis, having an actuating push rod, at the running-wheel end ofwhich a braking-blocking and/or steering-blocking formation is formed,the push rod also interacting with fork-mounted steering-blocking matingprotrusions.

A castor having a securing device of this type is known in a widevariety of embodiments; you are referred, for example, to DE-A 17 55 789and DE-A 23 47 900. These forerunners provide, as the usable functionalpositions, for the fork and the running wheel to be blocked, also forthe fork to be pivotable and the running wheel to be capable of runningfreely—the trailing side being formed of its own accord here—and finallyprovides for a position in which the pivoting movement of the fork isblocked and the castor can rotate freely. This renders a castor, for allpractical purposes, into a fixed castor. The actuating push rod, whichcan be moved into the different positions by a control cam which crossesover its axis, is subject to the action, in the restoring direction, ofa helical compression spring which is plugged on to the stem of the pushrod and is supported on a fork pin. Both the forerunners mentionedcomprise a large number of parts and therefore involve high productionand installation outlay.

SUMMARY OF THE INVENTION

It is an object of the invention to configure a castor of the generictype such that it is structurally more straightforward and morefavourable for installation.

This object is achieved first and foremost, in the case of a castor witha securing device having the features of claim 1, by a combination parton which both the steering-blocking mating protrusions and thebraking-blocking means, these being located in spaced-apart planes, areformed, the braking-blocking and/or steering-blocking formation of thepush rod being located in a neutral position between these planes. Sucha combination part reduces the number of parts. In addition, it performstasks which go beyond the introduction of forces for the push rod. Theabove-mentioned elements are additionally stabilised in relation to oneanother. This also serves to simplify the installation. The initialswitching state is a neutral position, from which the braking-blockingand/or steering-blocking formation can be displaced by an extremelyshort distance in opposite directions in order to move into therespective other functional position. It is advantageous then for thecombination part to be formed as an integral part. This can beaccomplished very well by moulding. Accordingly, it is not necessary forthe combination parts to be combined from a plurality of individualparts to form a structural unit. Such a multifunctional combination partis accommodated, for protection, in a freely moveable, but rotationallyblocked, manner in an inner space of the fork. The rotational blockingcan easily be achieved by utilising the parallel arrangement, which isusually present anyway, of the fork legs as guide surfaces. The movementis oriented vertically. For all practical purposes, the combination partis just fitted in and also secured. In this respect, it is provided thatthe combination part is fastened on the push rod. The fastening isresilient. The spring functions as a connecting element between thecombination part and the push rod. For long-term functioning, there isprovided a wire fastening spring which, in the fastening state, ispositioned in a circumferential groove of the push rod. Thecorresponding securing can be achieved, without the classic fasteningmeans, by the push rods, at the running-wheel end, having anintroduction cone for deflecting the wire spring in the course oflatching installation. A structurally advantageous solution is providedif the wire fastening spring is a U-clip, the U-crosspiece of which hasa deflection following approximately half the circumferential groove.This deflection is held securely in the region of the groove recess. Itis advantageous in terms of arrangement here for the U-legs of the wirefastening spring to be accommodated in retaining grooves of thecombination part. A further favourable feature of the invention is thatthe combination part has a braking section which is adapted to therunning-wheel curvature and is formed underneath the plane of thebraking-blocking means. This avoids exposed braking press-edges. Theactual braking surface may also be provided with roughened formations,for example transverse ribbing located parallel in space to thegeometrical axis of the running wheel. It is then provided that the wirespring passes through a chamber formed between the braking-blockingand/or steering-blocking formation and the braking section. This chamberis open in the direction away from the running wheel, so that the wirespring is accessible for release at all times. This facilitatesinstallation, and also any possible dismantling operation. This isbecause, once the running wheel has been removed, the combination partcan easily be drawn off, and replaced by a new combination part, in theaxial direction of the push rod. For position adjustment of the securingdevice, it proves favourable to provide on the combination part anadjusting screw for supporting and adjusting the combination part inrelation to a bearing or fork section of the castor, this section beingdisposed above the chamber. The adjustment is correspondingly stepless.The procedure here, in concrete terms, is such that the adjusting screwis accommodated by a thread in the combination part in the plane of thesteering-blocking means. To this extent, the adjusting screw is alsoaccommodated in a protected manner. The procedure here is also such thata through-passage opening is formed in the plane of the braking-blockingmeans in order to access the adjusting screw for actuation. Finally, theinvention proposes that the steering-blocking mating protrusions aredesigned for rotational blocking, defining at least one position, of thefork. A rotary latching position going beyond the 360° latching-positionwould then be located along the diametral line. Lastly, it provesadvantageous for precision rotational blocking to be provided betweenthe braking-blocking and/or steering-blocking formation and thebraking-blocking means, which is closer to the running wheel. As aresult, it is not just the case that the running wheel is braked, butalso, at the same time, that the fork is prevented from rotating.Classic radially oriented tooth/gap engagement may be provided here.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is explained in more detailhereinbelow with reference to an exemplary embodiment illustrated in thedrawing, in which:

FIG. 1 shows a vertical section through the castor with the push rodlocated in a neutral position,

FIG. 2 shows the same vertical section with the push rod located in arotation-blocking position,

FIG. 3 shows the same vertical section again with the push rod locatedin a braking position and with simultaneous rotational blocking of thefork of the castor,

FIG. 4 shows the combination part on its own, as seen in the directionof the chamber of the same, with associated wire spring,

FIG. 5 shows the section along line V—V in FIG. 4, without the spring,

FIG. 6 shows the plan view of FIG. 5,

FIG. 7 shows the plan view of the wire fastening spring, showing theU-shaped configuration,

FIG. 8 shows a view in the direction of the narrow side of the wirespring,

FIG. 9 shows a view in the direction of one of the U-legs of the wirespring,

FIG. 10 shows the actuating push rod on its own, to be precise in sideview,

FIG. 11 shows the section along line XI—XI in FIG. 10,

FIG. 12 shows the plan view of the push rod, and

FIG. 13 shows the bottom view of the push rod.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The castor 1 illustrated is provided with a securing device V. Thiseffects blocking of the running and/or steering action.

The blocking of the running action is correspondingly converted intobraking of a running wheel 2; the blocking of the steering action, incontrast, has the effect of securing a rotatably associated fork 3.

The running wheel 2 rotates about a horizontal geometrical axis x—x. Thecorresponding physical axis has the reference numeral 4.

The fork 3 pivots about a vertical geometrical axis y—y. This isembodied by an encased pin 5. The latter is positioned, in a manner inwhich it is secured against rotation, in an accommodating hollow of themobile object provided with the castors 1.

The geometrical axes x—x and y—y are spaced apart from one another tothe extent where the sought-after steerability which is typical ofcastors is achieved. The trailing side is on the left in the drawingillustration.

The pin 5 extends from the upper side of a bearing, preferably of a ballbearing 6. A perforated border 9 of a base 10 of the fork 3 is grippedand supported, with rotary mounting, between the upper race 7 and lowerrace 8 of the bearing.

The pin 5 has a push rod 11 passing through it. As can be gathered fromFIG. 12, the push rod has a non-round cross-section. An axially orientedguiding mount 12 in the pin 5 has a correspondingly contouredcross-section. The push rod 11, accordingly, is secured against rotationand can only be displaced vertically along the axis y—y.

The upper end of the push rod 11 merges into a screw-connected push-rodhead 13. This has a control cam 14 acting upon it. The latter is mountedfor rotary actuation about a horizontal geometric axis z—z. A hexagonalthrough-passage 15 is located in the centre of the control cam 14. Acorrespondingly cross-sectionally configured control shaft 16 of anactuating arrangement (not illustrated specifically) engages in thisthrough-passage.

The end surface of the basically disc-shaped control cam 14 hasdepressions 17 which are spaced apart by different distances from theaxis and in which a protrusion 18 of the push-rod head 13 engages, incontact therewith.

The appropriate contact pressure is achieved via the force of acompression spring 19. The latter subjects the push-rod head 13 toloading via its upper-end spring turn. The other, lower-end spring turnhas its castor-end abutment 20 in an annular channel of the upper end ofthe pin 5. The abutment at the upper end is provided by a stationarybearing location of the control shaft 16.

The end 11′ of the push rod 11, which is directed away from the runningwheel, can be adjusted axially in relation to the push-rod head 13, tobe precise via a threaded engagement 21 of two parts.

The running-wheel end, 11″ of the push rod 11 passes through the hole inthe region of the bearing, or ball bearing 6, and extends into theregion underneath the fork base 10. At this location, the said end 11″merges into a braking-blocking and/or steering-blocking formation 22.This is a horizontally oriented annular plate 23 which is rooted in thelateral wall of the push rod 11 and has, for all practical purposes, atooth-structure end border, for which you are referred to FIGS. 10, 12and 13. The structure comprises radially oriented protrusions 24projecting freely beyond the plate border. These protrusions aredisposed at identical angular spacing, but are of different widths. Thewider protrusions 24 extend along a common diametral line D—D. Thelatter coincides, in directional terms, with the flattening of the pushrod 11.

The steering-blocking formation 22 of the push rod 11, or theprotrusions 24 thereof, are associated with steering-blocking matingprotrusions 25. These are seated on a combination part K. Thesteering-blocking mating protrusions 25, leaving gaps corresponding tothe width of the protrusions 24, form a matching mating contour intowhich, with alignments appropriate for engagement and with acorresponding switch position of the control cam 14, the annular plate23 can latch.

The steering-blocking mating protrusions 25 are located in an upper decka of the combination part K.

A lower deck b extends at a vertical spacing therefrom. Braking-blockingand steering-blocking means 26 are realised on this lower deck. Thesemeans are accessible for push-rod actuation and are provided, inconcrete terms, in the form of a braking section 27.

With a corresponding switch position of the control cam 14, the push rod11 and vertically displaceable combination part K are positionedheightwise such that the braking-blocking and/or steering-blockingformation 22 of the push rod 11 is located in a neutral position (FIG.1), i.e. the annular plate 23 extends without contact between the twodecks a, b, that is to say between the spaced-apart planes of the two, asufficient free space 28 being left between these planes. The planes arerespectively designated E′—E′ and E″—E″.

The combination part K, which is formed as an integral part, for examplea plastics injection moulding, is accommodated in an inner space 29 ofthe fork 3 such that it can move freely in the vertical direction, butis rotationally blocked. The cross-sectional shape of the fork 3 isutilised for this purpose. This is made up, at least as far as an innercontour is concerned, of a circular-cylindrical section 3′ and twooutwardly leading, wing-like, rectilinear and parallel sections 3″. Thefirst-mentioned section 3′ extends over a good three-quarters of acircle and opens via parallel section 3″. The corresponding opening isdesignated 30 (see FIG. 6). A protrusion 31 which projects beyond thecircular outline of the vertically crosspiece-connected deck a and bprojects into this opening. As can be gathered, this protrusion has arotation-blocking effect.

The combination part K is thus guided and, furthermore, fastenedexclusively on the push rod 11. It is hung in the guiding inner space 29and the rotation-preventing opening 30 of the fork 3. The fastening isresilient, i.e. relative movements between the push rod 11 and thecombination part K are not prevented. A wire spring 32 serves forcorresponding fastening. This spring, in the fastening state, ispositioned in a circumferential groove 33 of the push rod 11, and moreprecisely of the running-wheel end 11″ of the latter. At therunning-wheel end, an introduction cone 34 is disposed upstream of saidend 11″. This introduction cone deflects the free-span U-crosspiece 32′of the wire spring 32, which is configured in the form of a U-clip, togive straightforward latching installation. As far as the clipconfiguration of the wire fastening spring 32 is concerned, you arereferred to FIG. 7. It can also be gathered there that the U-crosspiece32′ of the wire spring 32 has a deflection 32″ following approximatelyhalf the circumferential groove 33. The inner contour of this deflectioncorresponds essentially to the diameter of the base of thecircumferential groove 33.

The U-legs, which are angled in the same direction and are designated32′″, can also be gathered from the abovementioned figure. These U-legsare accommodated in matching, horizontally oriented retaining grooves 35of the combination part K. The retaining grooves 35 themselves form thepush-in limiting stop by way of the respective groove end. The grooveends are located such that the U-crosspiece 32′ intersects the axis y—y.The inlet of the retaining grooves 35 may diverge outwards to a slightextent in relation to the flanks of these grooves, so that introductionis facilitated. The U-legs 32′″ are expediently easy to move in theoutward direction. They thus have a clamping or gripping action inrelation to the retaining grooves 35.

The end of the ram 11 itself in this location, moreover, secures themerely plug-connected wire body from being lost since it is positionedwith blocking action upstream of the U-crosspiece 32′, which extends onthe trailing side of the castor 1.

As may further be gathered from the drawing illustration, thecombination part K has a braking section 27 adapted to the running-wheelcurvature. The braking section 27 extends underneath the plane E″—E″,that is to say that of the braking-blocking means 26. The brakingsection 27 carries transverse ribs 36, directed towards the runningsurface of the running wheel 2, with a correspondingly brake-enhancingaction.

The rear side of the wall forming the braking section 27 forms the lowertermination of the chamber 37 which is open on the widening-out sideand, in the upper region, has the U-crosspiece 32′ of the wire fasteningspring 32 passing through it. The groove 35 securing the spring body isspaced apart by such a distance that it is also still possible toachieve an upwardly directed movement of the push rod 11.

The braking-blocking and/or steering-blocking formation 22, which in thebasic position resides in the free space 28, can have its settingadjusted. For this purpose, an adjusting screw 38 is provided on thecombination part K. This screw supports the combination part K, whichis, as it were, suspended on the push rod 11, against the bearing orfork section, which is disposed above the chamber 37, of the castor 1,that is to say the lower race 8 of the ball bearing 6.

It can be gathered that the adjusting screw 38 is accommodated by athread in the combination part K in the plane E′—E′ of thesteering-blocking means, of the steering-blocking mating protrusions 25.The adjusting screw 38 still projects into the free space 28 by way ofits actuating end. In order to access the screw for adjustment purposes,a through-passage opening 39 for an adjusting tool on the deck b isformed in the plane E″—E″ of the braking-blocking means 26.

It should also be pointed out, as far as the braking-blocking means 26are concerned, that precision rotational blocking is provided betweenthe braking-blocking and/or steering-blocking formation 22 and thebraking-blocking means 26, which is closer to the running wheel.Radially oriented teeth 40 of a toothed rim thus extend from theunderside of the annular plate 23. This toothed rim extendsconcentrically in relation to the push rod 11. Said teeth 40 interactwith tooth gaps 41 on the upper side of the braking-blocking means 26,to be precise in the form of a congruent mating toothed rim.

The castor with a securing device V functions as follows: the switchposition in FIG. 1 allows the fork 3 to pivot freely and the runningwheel 2 to roll freely. In this position, the braking-blocking and/orsteering-blocking formation 22 has moved out of the region of action ofthe steering-blocking mating protrusions 25 and of the region of thebraking-blocking means 26. The push-rod 11 is stopped precisely in thisrespect against the control cam 14, in the direction of which it isloaded by the spring 19. Precision adjustment may, as has beendescribed, be carried out via the adjusting screw 38. The wire spring 32holds the combination part K precisely in a vertical position.

Rotation of the control cam 14 into the next position produces theposition which can be gathered from FIG. 2, in which exclusively thepivoting movement of the fork 3 is blocked. The spring 19 has displacedthe push rod 11, which is released to a corresponding extent, in theupward direction. The steering-blocking formation 22 moves with blockingaction into the steering-blocking mating protrusions 25. The wire spring32 is curved upwards, that is to say tensioned, in the region of itsU-crosspiece 32′ here. The force of the compression spring 19, however,is greater. It is not possible for the combination part K to bedisplaced upwards as well since it is supported on the ball bearing 6via adjusting screw 38. The running wheel 2 can be rotated freely.

FIG. 3 shows a position in which the running wheel 2 is braked androtation is blocked. The braking-blocking means 26 is pressed into therunning surface of the running wheel 2. The combination part K isdisplaced downwards by correspondingly downwardly directed displacementof the push rod 11, the annular plate 23 of which comes into contactwith the upper side of the braking-blocking means 26. This also takesplace counter to the restoring force of the compression spring 19 and ofthe wire fastening spring 32. Simultaneously or subsequently, the teeth40 also move into the tooth gaps 41, so that it is not only the casethat the running wheel 2 is braked, but also that the fork 3 isprevented from rotating. If teeth are positioned one upon the other,this produces the latching position along with the easily occurringresidual pivoting of the fork 3. The rotation-preventing means thenlatch in. This position is also produced by the rotary displacement ofthe control cam 14.

The rotational blocking of the fork 3, which produces the functioning ofa fixed castor, is achieved via the wider protrusions 24, which engagein correspondingly wider gaps of the steering-blocking matingprotrusions 25. At least one such latching-in position is provided. Thisis based on the main alignment of the mobile object.

I claim:
 1. Castor (1) comprising a running wheel, a fork holding thewheel, and a securing device (V) located adjacent to the wheel forblocking a running and/or a steering action of the running wheel (2),said fork (3) being pivotable about a vertical axis (y—y) of the castor,the castor further comprising a push rod (11) for actuating the securingdevice, and the securing device including steering-blocking matingprotrusions (25) and braking-blocking means (26) spaced apart from eachother along the vertical axis and being aligned with the fork, whereinthe securing device further comprises a braking-blocking and/orsteering-blocking formation (22) extending from the push rod in a planetransverse to the vertical axis, the push rod (11) also interacting withthe steering-blocking mating protrusions (25) of the securing device,wherein a combination part (K) is constituted by both thesteering-blocking mating protrusions (25) and the braking-blocking means(26) of the securing device that are located in spaced-apart planes(E′—E′, E″—E″), the braking-blocking and/or steering-blocking formation(22) of the push rod (11) being located in a neutral position betweenthe planes (E′—E′, E″—E″) during a running and a steering of the castorwheel, and wherein the combination part (K) is fastened on the push rod.2. The castor according to claim 1, wherein combination part (K) isformed as an integral part.
 3. The castor according to claim 1, whereinthe combination part (K) is accommodated in a freely moveable, butrotationally blocked, manner in an inner space (29) of the fork (3). 4.The castor according to claim 1, wherein the combination part (K) has abraking section (27), said braking section is adapted to a running-wheelcurvature and is formed underneath a first of said planes (E″—E″) of thebraking-blocking means (26).
 5. The castor according to claim 1, whereinfastening is resilient.
 6. The castor according to claim 1, wherein awire fastening spring (32), in a fastening state, is positioned in acircumferential groove (33) of the push rod (11).
 7. The castoraccording to claim 6, wherein the push rod (11), at the running-wheelend, has an introduction cone (34) for deflecting the wire fasteningspring (32) in a course of latching installation.
 8. The castoraccording to claim 6, wherein the wire fastening spring (32) is aU-clip, a U-crosspiece (32′) of the wire fastening spring (32) has adeflection (32″) following approximately half a second circumferentialgroove (35).
 9. The castor according to claim 6, wherein U-legs (32′″)of the wire fastening spring (32) are accommodated in retaining grooves(35) of the combination part (K).
 10. The castor according to claim 6,wherein the wire fastening spring (32) passes through a chamber (37)formed between the braking-blocking and/or steering-blocking formation(22) and a braking section (27).
 11. The castor according to claim 10,wherein provided on the combination part (K) is an adjusting screw (38)for supporting and adjusting the combination part (K) in relation to abearing or fork section of the castor (1), said section being disposedabove the chamber (37).
 12. The castor according to claim 11, whereinthe adjusting screw (38) is accommodated by a thread in the combinationpart (K) in one of said planes (E′—E′) of a steering-blocking means, ofthe steering-blocking mating protrusion (25).
 13. The castor accordingto claim 10, wherein a through-passage opening (39) is formed in a firstof said planes (E″—E″) of the braking-blocking means (26) in order toaccess the adjusting screw (38) for actuation.
 14. The castor accordingto claim 1, wherein the steering-blocking mating protrusions (25) areprovided for rotational blocking, defining at least one position, of thefork (3).
 15. The castor according to claim 1, wherein precisionrotational blocking is provided between the braking-blocking and/orsteering-blocking formation (22) and the braking-blocking means (26),which is closer to the running wheel.
 16. Castor (1) comprising arunning wheel, a fork holding the wheel, and a securing device (V)located adjacent to the wheel for blocking a running and/or a steeringaction of the running wheel (2), said fork (3) being pivotable about avertical axis (y—y) of the castor, the castor further comprising a pushrod (11) for actuating the securing device, and the securing deviceincluding steering-blocking mating protrusions (25) and braking-blockingmeans (26) spaced apart from each other along the vertical axis andbeing aligned with the fork, wherein the securing device furthercomprises a braking-blocking and/or steering-blocking formation (22)extending from the push rod in a plane transverse to the vertical axis,the push rod (11) also interacting with the steering-blocking matingprotrusions (25) of the securing device, wherein a combination part (K)is constituted by both the steering-blocking mating protrusions (25) andthe braking-blocking means (26) of the securing device that are locatedin spaced-apart planes (E′—E′, E″—E″), the braking-blocking and/orsteering-blocking formation (22) of the push rod (11) being located in aneutral position between the planes (E′—E′, E″—E″) during a running anda steering of the castor wheel, wherein the combination part furthercomprises a braking section extending from the braking-blocking meanstoward the wheel and being curved to mate with a curvature of the wheelupon being pressed toward the wheel by the push rod, the steeringblocking mating protrusions and the braking blocking means being formedas an integral assembly with the braking section.